The present invention relates to an ultrasonic driving motor in which a plurality of divided parts of a contact member are contacted with an ultrasonic vibrator by pressing with a ring-like elastic material, and a control apparatus is provided for driving the ultrasonic driving motor.
In an ultrasonic driving motor in the prior art, slide projections are made in the inside of a resilient ring frame of a rotor having a separated portion in the resilient ring frame, and the slide projections are pressed on a piezoelectric vibrator by opening the separated portion of the resilient ring frame. A rubber ring is inserted into a groove of the outside of the resilient ring frame, whereby the slide projections of the rotor are pressed on the piezoelectric vibrator.
In the ultrasonic driving motor, however, the rotor cannot be efficiently rotated by elliptically progressive waves generated on the edge of the piezoelectric vibrator, because the projections of the resilient ring frame of the rotor are contacted with the piezoelectric vibrator by leaving the spaces of the projections.